Recognition of the comparative effectiveness of medications has profound implications for both rational and cost-effective therapeutics, but without knowing the comparative risks of medications, benefit-risk estimates are necessarily incomplete. Unique among any other treated population, risks among pregnant women relate not just to the patient (the pregnant woman), but also to the fetus. Because premarketing studies don't and can't provide meaningful risk data, this task falls to the post marketing setting. Though the debacle of thalidomide in the early 1960s identified the devastating potential of medications to cause birth defects, more than four decades later there is no system in place to comprehensively assess the pregnancy safety of even relatively commonly used medications. Asthma is the most common chronic condition requiring medication treatment in pregnancy, yet we know little about the risks to the fetus of current and newly introduced asthma medications. Using an established case control surveillance study of specific drug exposures in relation to specific birth defects (the Slone Epidemiology Center Birth Defects Study, BDS), we seek to demonstrate its ability to assess, in a systematic, efficient, and valid manner, the risks and safety of various asthma medications in relation to specific birth defects. In addition to capturing information on actual use of medications (including prescription, over-the counter, and herbals) and validating birth defects through medical record review, this study will use a validated questionnaire to assess asthma control and capture information on important confounders-such as smoking and periconceptional folate consumption-that are critical to the consideration of birth defects. Further, the project will work closely with the OTIS Pregnancy Registries and the American Academy of Asthma, Allergy, and Immunology (AAAAI) to demonstrate the feasibility and value of the Asthma and Allergy Medications in Pregnancy Safety Surveillance (AAMPSS) approach, a collaborative system involving two complementary data collection methods (BDS case-control surveillance and OTIS pregnancy registries) combined into a common infrastructure that includes an Independent Advisory Committee (to be coordinated by the AAAAI). The success of this demonstration project will lead to an ongoing, comprehensive, and valid system to assess the fetal risks associated with the wide range of medications (beyond asthma), and will permit comparative effectiveness measures to finally include critically important information on the risks and safety of medications taken by pregnant women.